In Europe, while Siddique was working on his post-doctoral research at the
Paris University, he had the opportunity to meet with the members of "
The Paris Group" where he had led the discussions on
unsolved problems in physics and
in mathematics. During his stay in Great Britain, he studied Quantum mechanics and published scientific papers at the Cavendish Laboratory.
Return to India In 1931, Siddiqui then returned to Hyderabad, British Indian Empire, and joined Osmania University there as an
associate professor of mathematics. In 1964, he moved to Islamabad, where he joined PAEC. There he began his academic research in theoretical physics. With the establishment of TPG, Siddiqui began to work with Abdus Salam, and on his advice began research in Theoretical Physics at PAEC. During the 1970s, Siddiqui worked on problems in theoretical physics with Pakistani theoretical physicists in the
nuclear weapons programme. At PAEC, he became a mentor to some of the country's academic scientists. At PAEC, he was the director of the Mathematical Physics Group (MPG) and was tasked with performing mathematical calculations involved in
nuclear fission and
supercomputing. While both MPG and Theoretical Physics Group (TPG) had reported directly to Abdus Salam, Siddiqui co-ordinated each meeting with the scientists of TPG and mathematicians of the MPG. At PAEC, he directed the mathematical research
directly involving the theory of
general relativity, and helped establish the
quantum computers laboratories at PAEC. Since theoretical physics plays a major role in identifying the parameters of nuclear physics, Siddiqui started the work on special relativity's complex applications, the '
relativity of simultaneity'. His Mathematical Physics Group undertook the research and performed calculations on the 'relativity of simultaneity' during the process of weapon detonation, where multiple explosive energy rays are bound to release in the same isolate and close medium at the same time interval.
Post-war After his work at PAEC, Siddiqui again joined Quaid-e-Azam University's Physics Faculty. As professor of physics, he continued his research at the Institute of Physics, QAU. He helped develop the higher education sector, and placed mainframe policies in the institution. ==Death and legacy==